drivers/video/backlight/backlight.c

   1 /*
   2  * Backlight Lowlevel Control Abstraction
   3  *
   4  * Copyright (C) 2003,2004 Hewlett-Packard Company
   5  *
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/init.h>
  10 #include <linux/device.h>
  11 #include <linux/backlight.h>
  12 #include <linux/notifier.h>
  13 #include <linux/ctype.h>
  14 #include <linux/err.h>
  15 #include <linux/fb.h>
  16
  17 #ifdef CONFIG_PMAC_BACKLIGHT
  18 #include <asm/backlight.h>
  19 #endif
  20
  21 #if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
  22                            defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
  23 /* This callback gets called when something important happens inside a
  24  * framebuffer driver. We're looking if that important event is blanking,
  25  * and if it is, we're switching backlight power as well ...
  26  */
  27 static int fb_notifier_callback(struct notifier_block *self,
  28                                 unsigned long event, void *data)
  29 {
  30         struct backlight_device *bd;
  31         struct fb_event *evdata = data;
  32
  33         /* If we aren't interested in this event, skip it immediately ... */
  34         if (event != FB_EVENT_BLANK && event != FB_EVENT_CONBLANK)
  35                 return 0;
  36
  37         bd = container_of(self, struct backlight_device, fb_notif);
  38         mutex_lock(&bd->ops_lock);
  39         if (bd->ops)
  40                 if (!bd->ops->check_fb ||
  41                     bd->ops->check_fb(evdata->info)) {
  42                         bd->props.fb_blank = *(int *)evdata->data;
  43                         backlight_update_status(bd);
  44                 }
  45         mutex_unlock(&bd->ops_lock);
  46         return 0;
  47 }
  48
  49 static int backlight_register_fb(struct backlight_device *bd)
  50 {
  51         memset(&bd->fb_notif, 0, sizeof(bd->fb_notif));
  52         bd->fb_notif.notifier_call = fb_notifier_callback;
  53
  54         return fb_register_client(&bd->fb_notif);
  55 }
  56
  57 static void backlight_unregister_fb(struct backlight_device *bd)
  58 {
  59         fb_unregister_client(&bd->fb_notif);
  60 }
  61 #else
  62 static inline int backlight_register_fb(struct backlight_device *bd)
  63 {
  64         return 0;
  65 }
  66
  67 static inline void backlight_unregister_fb(struct backlight_device *bd)
  68 {
  69 }
  70 #endif /* CONFIG_FB */
  71
  72 static ssize_t backlight_show_power(struct class_device *cdev, char *buf)
  73 {
  74         struct backlight_device *bd = to_backlight_device(cdev);
  75
  76         return sprintf(buf, "%d\n", bd->props.power);
  77 }
  78
  79 static ssize_t backlight_store_power(struct class_device *cdev, const char *buf, size_t count)
  80 {
  81         int rc = -ENXIO;
  82         char *endp;
  83         struct backlight_device *bd = to_backlight_device(cdev);
  84         int power = simple_strtoul(buf, &endp, 0);
  85         size_t size = endp - buf;
  86
  87         if (*endp && isspace(*endp))
  88                 size++;
  89         if (size != count)
  90                 return -EINVAL;
  91
  92         mutex_lock(&bd->ops_lock);
  93         if (bd->ops) {
  94                 pr_debug("backlight: set power to %d\n", power);
  95                 bd->props.power = power;
  96                 backlight_update_status(bd);
  97                 rc = count;
  98         }
  99         mutex_unlock(&bd->ops_lock);
 100
 101         return rc;
 102 }
 103
 104 static ssize_t backlight_show_brightness(struct class_device *cdev, char *buf)
 105 {
 106         struct backlight_device *bd = to_backlight_device(cdev);
 107
 108         return sprintf(buf, "%d\n", bd->props.brightness);
 109 }
 110
 111 static ssize_t backlight_store_brightness(struct class_device *cdev, const char *buf, size_t count)
 112 {
 113         int rc = -ENXIO;
 114         char *endp;
 115         struct backlight_device *bd = to_backlight_device(cdev);
 116         int brightness = simple_strtoul(buf, &endp, 0);
 117         size_t size = endp - buf;
 118
 119         if (*endp && isspace(*endp))
 120                 size++;
 121         if (size != count)
 122                 return -EINVAL;
 123
 124         mutex_lock(&bd->ops_lock);
 125         if (bd->ops) {
 126                 if (brightness > bd->props.max_brightness)
 127                         rc = -EINVAL;
 128                 else {
 129                         pr_debug("backlight: set brightness to %d\n",
 130                                  brightness);
 131                         bd->props.brightness = brightness;
 132                         backlight_update_status(bd);
 133                         rc = count;
 134                 }
 135         }
 136         mutex_unlock(&bd->ops_lock);
 137
 138         return rc;
 139 }
 140
 141 static ssize_t backlight_show_max_brightness(struct class_device *cdev, char *buf)
 142 {
 143         struct backlight_device *bd = to_backlight_device(cdev);
 144
 145         return sprintf(buf, "%d\n", bd->props.max_brightness);
 146 }
 147
 148 static ssize_t backlight_show_actual_brightness(struct class_device *cdev,
 149                                                 char *buf)
 150 {
 151         int rc = -ENXIO;
 152         struct backlight_device *bd = to_backlight_device(cdev);
 153
 154         mutex_lock(&bd->ops_lock);
 155         if (bd->ops && bd->ops->get_brightness)
 156                 rc = sprintf(buf, "%d\n", bd->ops->get_brightness(bd));
 157         mutex_unlock(&bd->ops_lock);
 158
 159         return rc;
 160 }
 161
 162 static void backlight_class_release(struct class_device *dev)
 163 {
 164         struct backlight_device *bd = to_backlight_device(dev);
 165         kfree(bd);
 166 }
 167
 168 static struct class backlight_class = {
 169         .name = "backlight",
 170         .release = backlight_class_release,
 171 };
 172
 173 #define DECLARE_ATTR(_name,_mode,_show,_store)                  \
 174 {                                                               \
 175         .attr   = { .name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE },  \
 176         .show   = _show,                                        \
 177         .store  = _store,                                       \
 178 }
 179
 180 static const struct class_device_attribute bl_class_device_attributes[] = {
 181         DECLARE_ATTR(power, 0644, backlight_show_power, backlight_store_power),
 182         DECLARE_ATTR(brightness, 0644, backlight_show_brightness,
 183                      backlight_store_brightness),
 184         DECLARE_ATTR(actual_brightness, 0444, backlight_show_actual_brightness,
 185                      NULL),
 186         DECLARE_ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
 187 };
 188
 189 /**
 190  * backlight_device_register - create and register a new object of
 191  *   backlight_device class.
 192  * @name: the name of the new object(must be the same as the name of the
 193  *   respective framebuffer device).
 194  * @devdata: an optional pointer to be stored in the class_device. The
 195  *   methods may retrieve it by using class_get_devdata(&bd->class_dev).
 196  * @ops: the backlight operations structure.
 197  *
 198  * Creates and registers new backlight class_device. Returns either an
 199  * ERR_PTR() or a pointer to the newly allocated device.
 200  */
 201 struct backlight_device *backlight_device_register(const char *name,
 202         struct device *dev,
 203         void *devdata,
 204         struct backlight_ops *ops)
 205 {
 206         int i, rc;
 207         struct backlight_device *new_bd;
 208
 209         pr_debug("backlight_device_alloc: name=%s\n", name);
 210
 211         new_bd = kzalloc(sizeof(struct backlight_device), GFP_KERNEL);
 212         if (!new_bd)
 213                 return ERR_PTR(-ENOMEM);
 214
 215         mutex_init(&new_bd->update_lock);
 216         mutex_init(&new_bd->ops_lock);
 217         new_bd->ops = ops;
 218         new_bd->class_dev.class = &backlight_class;
 219         new_bd->class_dev.dev = dev;
 220         strlcpy(new_bd->class_dev.class_id, name, KOBJ_NAME_LEN);
 221         class_set_devdata(&new_bd->class_dev, devdata);
 222
 223         rc = class_device_register(&new_bd->class_dev);
 224         if (rc) {
 225                 kfree(new_bd);
 226                 return ERR_PTR(rc);
 227         }
 228
 229         rc = backlight_register_fb(new_bd);
 230         if (rc) {
 231                 class_device_unregister(&new_bd->class_dev);
 232                 return ERR_PTR(rc);
 233         }
 234
 235
 236         for (i = 0; i < ARRAY_SIZE(bl_class_device_attributes); i++) {
 237                 rc = class_device_create_file(&new_bd->class_dev,
 238                                               &bl_class_device_attributes[i]);
 239                 if (rc) {
 240                         while (--i >= 0)
 241                                 class_device_remove_file(&new_bd->class_dev,
 242                                                          &bl_class_device_attributes[i]);
 243                         class_device_unregister(&new_bd->class_dev);
 244                         /* No need to kfree(new_bd) since release() method was called */
 245                         return ERR_PTR(rc);
 246                 }
 247         }
 248
 249 #ifdef CONFIG_PMAC_BACKLIGHT
 250         mutex_lock(&pmac_backlight_mutex);
 251         if (!pmac_backlight)
 252                 pmac_backlight = new_bd;
 253         mutex_unlock(&pmac_backlight_mutex);
 254 #endif
 255
 256         return new_bd;
 257 }
 258 EXPORT_SYMBOL(backlight_device_register);
 259
 260 /**
 261  * backlight_device_unregister - unregisters a backlight device object.
 262  * @bd: the backlight device object to be unregistered and freed.
 263  *
 264  * Unregisters a previously registered via backlight_device_register object.
 265  */
 266 void backlight_device_unregister(struct backlight_device *bd)
 267 {
 268         int i;
 269
 270         if (!bd)
 271                 return;
 272
 273         pr_debug("backlight_device_unregister: name=%s\n", bd->class_dev.class_id);
 274
 275 #ifdef CONFIG_PMAC_BACKLIGHT
 276         mutex_lock(&pmac_backlight_mutex);
 277         if (pmac_backlight == bd)
 278                 pmac_backlight = NULL;
 279         mutex_unlock(&pmac_backlight_mutex);
 280 #endif
 281
 282         for (i = 0; i < ARRAY_SIZE(bl_class_device_attributes); i++)
 283                 class_device_remove_file(&bd->class_dev,
 284                                          &bl_class_device_attributes[i]);
 285
 286         mutex_lock(&bd->ops_lock);
 287         bd->ops = NULL;
 288         mutex_unlock(&bd->ops_lock);
 289
 290         backlight_unregister_fb(bd);
 291
 292         class_device_unregister(&bd->class_dev);
 293 }
 294 EXPORT_SYMBOL(backlight_device_unregister);
 295
 296 static void __exit backlight_class_exit(void)
 297 {
 298         class_unregister(&backlight_class);
 299 }
 300
 301 static int __init backlight_class_init(void)
 302 {
 303         return class_register(&backlight_class);
 304 }
 305
 306 /*
 307  * if this is compiled into the kernel, we need to ensure that the
 308  * class is registered before users of the class try to register lcd's
 309  */
 310 postcore_initcall(backlight_class_init);
 311 module_exit(backlight_class_exit);
 312
 313 MODULE_LICENSE("GPL");
 314 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
 315 MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");